Regenerated elastic roller manufacturing process, regenerated elastic roller, electropohotographic process cartridge, and electropohotographic image forming apparatus

ABSTRACT

A regenerated elastic rollers manufacturing process is provided. The process includes the step of removing an agglutinated stain of toner adhered to the surface of an elastic roller including a mandrel and an elastic layer. The step further includes the steps of: (1) pressing a pressing roller against the surface of the elastic roller so as to crack the agglutinated stain on the surface of the elastic roller; and (2) removing the agglutinated stain cracked in the step (1) from the surface of the elastic roller by means of an adhesive roller.

This application is a divisional of U.S. application Ser. No. 12/179,018filed on Jul. 24, 2008, which is a continuation of InternationalApplication No. PCT/JP2008/051139 filed on Jan. 21, 2008, which claimsthe benefit of Japanese Patent Application No. 2007-011914 filed on Jan.22, 2007 and Japanese Patent Application No. 2008-008346 filed on Jan.17, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a regenerated elastic roller manufacturingprocess by which elastic rollers having been used in image formingapparatuses utilizing an electrophotographic system, such as copyingmachines, laser beam printers, facsimile machines and printing machines,can be recovered. This invention also relates to a regenerated elasticroller, and an electrophotographic process cartridge and anelectrophotographic image forming apparatus both of which use theregenerated elastic roller.

2. Description of the Related Art

In the image forming apparatus utilizing an electrophotographic system,such as electrophotographic apparatus, as a developing roller, acharging roller, a transfer roller, a fixing roller or a cleaningroller, an elastic roller comprising an elastic layer as a surfacelayer, hereinafter called as a “surface-elastic roller”, is used. To theouter peripheral surface of the surface-elastic roller, toners, externaladditives and so forth making up developers adhere and are graduallydeposited while being used. In the image forming apparatus, the surfaceof the surface-elastic roller is usually cleaned with cleaning means ofvarious types (see Japanese Patent Applications Laid-Open No. H09-101659and No. H04-336582). However, it has come about that, when being usedover a long period of time, developer components such as toners,external additives and so forth which have been unable to be removed bycleaning means are adhered and agglutinated in some cases to the surfaceof the surface-elastic roller. In particular, there is a remarkabletendency in a developing roller that crushed toners are agglutinated onthe surface thereof. Hereinafter, the agglutinated matters on thesurface of the surface-elastic roller are called an “agglutinated stainof a developer origin” or simply an “agglutinated stain”.

Such an agglutinated stain of developer origin is difficult to removewith such cleaning means as disclosed in the above Japanese PatentApplications Laid-Open No. H09-101659 and No. H04-336582.

However, from the viewpoint of reducing an environmental load, there isa growing need for developing a technique that enables thesurface-elastic roller on the surface of which the agglutinated stain isformed to be re-applied for forming a high-grade electrophotographicimages. Japanese Patent Application Laid-Open No. H08-328375 discloses atechnique in which a filming on a developing roller having been used isremoved to regenerate the developing roller. More specifically, itdiscloses a method in which the surface of a developing roller havingbeen used is surface-processed with a tape abrasive, water jets or agrinding stone to regenerate the developing roller.

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

However, the method disclosed in the above Japanese Patent ApplicationLaid-Open No. H08-328375 is basically a method of scraping off theagglutinated stain of a developer origin. According to the presentinventors' study, when the method is applied to a surface-elasticroller, it has come about in some case that the surface of its elasticlayer is damaged or scratched. If a charging roller or a developingroller has irregular scratches or the like on the surface thereof, itmay cause non-uniform charging or non-uniform development to affect thegrade of images.

Accordingly, an object of the present invention is to provide a processof manufacturing a regenerated elastic roller which can be reused asvarious elastic rollers of an image forming apparatus utilizing anelectrophotographic process.

Another object of the present invention is to provide anelectrophotographic process cartridge and an electrophotographic imageforming apparatus which enable effective utilization of resources to bepromoted by the use of the regenerated elastic roller obtained.

Means for Resolving the Problem

The regenerated elastic roller manufacturing process according to thepresent invention includes the step of removing an agglutinated stain ofa developer origin adhered to the surface of an elastic roller providedwith a mandrel and an elastic layer as a surface layer, which includesthe steps of: (1) pressing a pressing roller against the surface of theelastic roller so as to crack the agglutinated stain on the surface ofthe elastic roller; and (2) removing the agglutinated stain cracked inthe step (1) from the surface of the elastic roller by means of anadhesive roller.

The regenerated elastic roller according to the present invention ischaracterized in that it has been manufactured by the above regeneratedelastic roller manufacturing process.

Further, the electrophotographic process cartridge according to thepresent invention includes a photosensitive member on which anelectrostatic latent image is to be formed, a charging member whichcharges the photosensitive member and a developing member which developsthe electrostatic latent image held on the photosensitive member, and isdetachably mountable on the main body of an electrophotographic imageforming apparatus, wherein at least one of the charging member and thedeveloping member is the above regenerated elastic roller.

Furthermore, the electrophotographic image forming apparatus accordingto the present invention includes a photosensitive member on which anelectrostatic latent image is to be formed, a charging member whichcharges the photosensitive member and a developing member which developsthe electrostatic latent image held on the photosensitive member,wherein at least one of the charging member and the developing member isthe above regenerated elastic roller.

According to the present invention, the agglutinated stain can beremoved from the surface of the surface-elastic roller withoutphysically damaging the elastic rollers and without impairing theproperties, and as the result of that, a regenerated elastic roller,which can be reused as various elastic rollers of an image formingapparatus utilizing an electrophotographic process, is obtained. Inaddition, the electrophotographic process cartridge andelectrophotographic image forming apparatus of the present invention canpromote effective utilization of resources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic sectional view of an example of an elastic rollerin its axial direction, used in the regenerated elastic rollermanufacturing process of the present invention.

FIG. 1B is a schematic sectional view of an example of the elasticroller in the direction crossing at right angles to its axis, used inthe regenerated elastic roller manufacturing process of the presentinvention.

FIG. 2A is a schematic sectional view of an example of a pressing rollerin its axial direction, used in the regenerated elastic rollermanufacturing process of the present invention.

FIG. 2B is a schematic sectional view of an example of the pressingroller in the direction crossing at right angles to its axis, used inthe regenerated elastic roller manufacturing process of the presentinvention.

FIG. 3A is a schematic sectional view of an example of an adhesiveroller in its axial direction, used in the regenerated elastic rollermanufacturing process of the present invention.

FIG. 3B is a schematic sectional view of an example of the adhesiveroller in the direction crossing at right angles to its axis, used inthe regenerated elastic roller manufacturing process of the presentinvention.

FIG. 4 is a schematic structural view showing an example of aregenerated elastic roller manufacturing unit to which the regeneratedelastic roller manufacturing process of the present invention isapplied.

FIG. 5 is a schematic structural view showing another example of aregenerated elastic roller manufacturing unit to which the regeneratedelastic roller manufacturing process of the present invention isapplied.

FIG. 6 is a schematic structural view showing still another example of aregenerated elastic roller manufacturing unit to which the regeneratedelastic roller manufacturing process of the present invention isapplied.

FIG. 7 is a schematic structural view showing an example of anelectrophotographic image forming apparatus of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The regenerated elastic roller manufacturing process according to thepresent invention has the step of removing an agglutinated stain of adeveloper origin adhered to the surface of an elastic roller providedwith a mandrel and an elastic layer as a surface layer.

That step includes the following steps (1) and (2):

(1) pressing a pressing roller against the surface of the elastic rollerso as to crack the agglutinated stain on the surface of the elasticroller; and

(2) removing the agglutinated stain cracked in the step (1) from thesurface of the elastic roller by means of an adhesive roller.

The present inventors have discovered that the agglutinated stain can beremoved from the surface-elastic roller without damaging the elasticroller by applying a load with a pressing roller to the surface-elasticroller on the surface of which the agglutinated stain of a developerorigin is adhered because of repetitive use for the electrophotographicprocess, and then, contacting an adhesive roller comprising an adhesivelayer with the surface of the elastic roller.

As to the reason why the agglutinated stain of a developer origin canefficiently be removed by the above process, and as the result, ahigh-grade regenerated elastic roller can be obtained, the presentinventors consider the following:

Most of the agglutinated stain of a developer origin that has beenformed on the elastic roller surface is pressed against theelectrophotographic photosensitive member or the like to come into alaminar agglutinated stain, which adheres strongly to the surface of theelastic roller. Hence, if the adhesive roller is merely used, theagglutinated stain cannot sufficiently be removed when the adhesiveforce of the agglutinated stain to the elastic roller surface isstronger than the adhesive force of the agglutinated stain to theadhesive roller. However, pressure is applied to the elastic rollersurface to locally deform the elastic roller, whereupon the agglutinatedstain whose flexibility is lower as compared with the elastic roller canno longer follow the deformation of the elastic roller and is broken, sothat the agglutinated stain on the surface is cracked. The crackedagglutinated stain is reduced in the adhesive force to the elasticroller. Hence, the agglutinated stain is considered to be efficientlyremoved by means of the adhesive roller.

Herein, the “crack(s)” referred to in the present invention is definedas a crack(s) of the agglutinated stain that is(are) not seen beforepassing through the step (1), but is(are) seen after passing through thestep (1), when the agglutinated stain on the elastic roller surface isobserved with a scanning electron microscope (SEM) at 5,000magnifications.

According to studies made by the present inventors, cracking theagglutinated stain on the elastic roller in this way has been found tobe very important in removing the agglutinated stain in the step oftransfer the agglutinated stain to the surface of the adhesive rolleraccording to the step (2).

—Elastic Roller—

The elastic roller to be recovered in the regenerated elastic rollermanufacturing process according to the present invention is of varioustypes set in the electrophotographic image forming apparatus utilizingan electrophotographic process. Specifically, the elastic rollerincludes developing rollers, charging rollers, transfer rollers, fixingrollers and cleaning rollers. Such an elastic roller has a mandrel andan elastic layer which is a surface layer formed on the periphery of themandrel.

Mandrel:

The mandrel supports the elastic layer and so forth on its periphery andhas a strength large enough to withstand a load applied in theelectrophotographic process. The mandrel may have any shape such as acolumn or a cylinder.

The material of the mandrel includes carbon steel, alloy steel, castiron and conductive resins where the elastic roller is required to haveelectrical conductivity.

Specific examples of the alloy steel includes stainless steel, nickelchromium steel, nickel chromium molybdenum steel, chromium steel,chromium molybdenum steel, and nitriding steel to which Al, Cr, Mo and Vhave been added.

The mandrel may have been subjected to plating or oxidation treatment asa measure for antirust. The type of plating includes electroplating andelectroless plating. The electroless plating is preferred from theviewpoint of dimensional stability. As the electroless plating, thefollowing may be used: nickel plating such as Ni—P, Ni—B, Ni—W—P orNi—P—PTFE composite plating, copper plating, gold plating, Kanigenplating, and other alloy plating of various types. The deposit thicknessin the plating is preferably 0.05 μm or more, and more preferably from0.1 μm to 30 μm.

Elastic Layer:

The elastic layer is provided in order to provide the elastic rollerwith elasticity required in the apparatus to be used. The elastic layermay specifically be made up of any of a solid member and a foamedmember. The elastic layer may also be composed of a single layer or aplurality of layers. For example, the developing roller is always incontact with a photosensitive drum, a developer control blade and atoner, and hence, is provided with the elastic layer so as to lessendamage occurring between these members and to achieve low hardness andlow compression set.

A material for the elastic layer includes, e.g., natural rubber,isoprene rubber, styrene rubber, butyl rubber, butadiene rubber,fluoro-rubber, urethane rubber and silicone rubber. Any of these may beused singly or in a combination of two or more.

Conductive Agent, Etc:

The elastic layer may be incorporated with a conductive agent,nonconductive filler and, as other various additive components necessaryfor molding, a cross-linking agent, a catalyst, a dispersion promoterand so forth, in accordance with the performance required for theelastic roller.

As the conductive agent, the following may be used: various conductivemetals or alloys, conductive metal oxides, electron-conductive agentssuch as fine insulating material powders coated with these, andion-conductive agents.

The ion-conductive agents may be exemplified by the following.

Salts of Group 1 metals of the periodic table, such as LiCF₃SO₃, NaClO₄,LiClO₄, LiAsF₆, LiBF₄, NaSCN, KSCN and NaCl; ammonium salts such asNH₄Cl, (NH₄)₂SO₄ and NH₄NO₃; salts of Group 2 metals of the periodictable, such as Ca(ClO₄)₂ and Ba(Clo₄)₂; complexes of these salts withpolyhydric alcohols such as 1,4-butanediol, ethylene glycol,polyethylene glycol, propylene glycol or polypropylene glycol, or withderivatives of these; complexes of these salts with monohydric alcoholssuch as ethylene glycol monomethyl ether, ethylene glycol monoethylether, polyethylene glycol monomethyl ether or polyethylene glycolmonoethyl ether; cationic surface-active agents such as quaternaryammonium salts; anionic surface-active agents such as aliphaticsulfonates, alkyl sulfuric ester salts and alkyl phosphoric ester salts;and amphoteric surface-active agents such as betaine.

The electron-conductive agents may be exemplified by the following.

Carbon type materials such as carbon black and graphite; metals oralloys, such as aluminum, silver, gold, a tin-lead alloy and acopper-nickel alloy; metal oxides such as zinc oxide, titanium oxide,aluminum oxide, tin oxide, antimony oxide, indium oxide and silveroxide; and materials obtained by subjecting fillers of various types toconductive metal plating with use of copper, nickel or silver.

Any of these conductive agents may be used singly or in a combination oftwo or more, in the form of powder or fiber. Of these, carbon black ispreferred because conductivity is easily controlled and is economical.

Incorporation of such a conductive agent enables the elastic layer tohave, e.g., a volume resistivity of from 1×10⁴ to 1×10¹⁰ Ω·cm. Adeveloping roller the elastic layer of which has volume resistivitywithin this range has uniform charge controllability for toners. Theelastic layer of the developing roller preferably has a volumeresistivity of from 1×10⁴ to 1×10⁹ Ω·cm.

Examples of the non-conductive filler include the following:Diatomaceous earth, quartz powder, dry-process silica, wet-processsilica, titanium oxide, zinc oxide, aluminosilicic acid, calciumcarbonate, zirconium silicate, aluminum silicate, talc, aluminum oxide,and iron oxide.

The elastic layer has elasticity required for the elastic roller, andpreferably has, e.g., an Asker-C hardness of 10 degrees or more and 80degrees or less. As long as the elastic layer has an Asker-C hardness of10 degrees or more, any oil components can be kept from oozing out ofthe rubber material making up the elastic layer, and the photosensitivedrum can be kept from being contaminated. As long as the elastic layerhas an Asker-C hardness of 80 degrees or less, toners can effectively bekept from deteriorating, and reproduced images can be inhibited fromdecreasing in image quality.

The Asker-C hardness herein referred to may be defined by the valuemeasured with an Asker rubber hardness meter (manufactured by KobunshiKeiki Co., Ltd.), using a test piece prepared separately according to areference standard Asker-C Type SRIS (Japan Rubber Association Standard)0101.

The elastic layer is preferably in a thickness of 0.5 mm or more and 50mm or less, and more preferably 0.5 mm or more and 10 mm or less, in thecase of, e.g., the developing roller.

The method of forming the elastic layer includes, e.g., a method inwhich an uncured elastic layer material is heat-cured by any one ofvarious types of molding methods, such as extrusion, press molding,injection molding, liquid injection molding or cast molding, at asuitable temperature for a suitable time to form the elastic layer onthe mandrel. The uncured elastic layer material may be injected into acylindrical mold with the mandrel set therein and then heat-cured,whereby the elastic layer can be formed in a high precision on theperiphery of the mandrel.

—Functional Layer—

The elastic roller may be provided with one or two or more types offunctional layers over or under the elastic layer so as to havefunctionality as required.

The functional layer includes a surface layer which protects the elasticroller surface, provides the surface with wear resistance and keepstoners from adhering thereto.

Examples of a binder resin for the surface layer include the following:Epoxy resins, diallyl phthalate resins, polycarbonate resins, fluorineresins, polypropylene resins, urea resins, melamine resins, siliconresins, polyester resins, styrol type resins, vinyl acetate resins,phenolic resins, polyamide resins, cellulose type resins, urethaneresins, silicone resins, acrylic urethane resins, and emulsion resins; acombination of two or more selected from these.

Of these, nitrogen-containing resins such as urethane resins and acrylicurethane resins are preferred. This is because, in the case of thedeveloping roller, toners can stably be charged, toners can be kept fromadhering as being of low tackiness, and further toners are easy torelease.

The urethane resins used here are obtained from isocyanate compounds andpolyols.

Where a surface layer containing a urethane resin as the binder resin isformed on the elastic layer, it is preferable that the surface of theelastic layer is irradiated with ultraviolet rays and thereafter acoating film is formed from a coating solution containing an uncuredresin material. Hydroxyl groups that form chemical bonds with theisocyanate included in the urethane resin can be easily generated byirradiation with ultraviolet rays to obtain a strong linkage between aurethane resin layer and the elastic layer.

Examples of the isocyanate include the following:Diphenylmethane-4,4′-diisocyanate, 1,5-naphthalene diisocyanate,3,3′-dimethylbiphenyl-4,4′-diisocyanate, 4,4′-dicyclohexylmettanediisocyanate, p-phenylene diisocyanate, isophorone diisocyanate,carbodimide modified MDI, xylylene diisocyanate, trimethylhexamethylenediisocyanate, tolylene diisocyanate, naphthylene diisocyanate,paraphenylene diisocyanate, hexamethylene diisocyanate, andpolymethylene polyphenyl polyisocyanate. Any of these may be used singlyor in a combination of two or more.

Examples of the polyol include the following: As dihydric polyols(diols), ethylene glycol, diethylene glycol, propylene glycol,dipropylene glycol, 1,4-butanediol, hexanediol, neopentyl glycol,1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylene glycol, andtriethylene glycol; as trihydric or higher polyols,1,1,1-trimethylolpropane, glycerol, pentaerythritol, and sorbitol; andfurther polyols such as high molecular weight polyethylene glycolsobtained by addition of ethylene oxide or propylene oxide to diols ortriols, polypropylene glycol, ethylene oxide-propylene oxide blockglycol. Any of these may be used in combination, where the mixingproportion thereof may appropriately be determined.

As these urethane resins, it is preferable to use as a main component aresin obtained by mixing a polyurethane prepolymer having a hydroxylgroup at least at the terminal and a block isocyanate in a proportion offrom 1.1 to 1.5 in NCO equivalent weight (the value of [NCO]/[OH]) andallowing them to react. As long as the NCO equivalent weight is 1.1 ormore, the surface layer can have adhesion to the elastic layer and canbe inhibited from being damaged against repeated regenerationprocessing. As long as the NCO equivalent weight is 1.5 or less, thesurface layer can be kept from having a high hardness and theagglutinated stain of toner is made readily removable because of theeffect of pressing the pressing roller.

The surface layer may contain a conductive agent in order to control theelectrical resistance of the elastic roller. The conductive agent thesurface layer may contain is specifically exemplified by the same onesas exemplified as the conductive agent used in the elastic layer.

The surface layer is preferably in a thickness of from 1 μm to 500 μm,and more preferably from 1 μm to 50 μm. As long as the surface layer isin a thickness of 1 μm or more, the elastic roller can be inhibited fromdeteriorating because of wear or the like, and comes to be superior indurability. As long as the surface layer has a thickness of 500 μm orless, the elastic roller surface can be inhibited from having a highhardness and from deteriorating, and toners can be inhibited frommelt-adhering to the surface.

As a method for forming the surface layer, a method is available inwhich, e.g., a coating solution containing an uncured resin is preparedand the surface layer is formed by coating such as dipping, rollcoating, ring coating or spraying.

Surface Roughness (Ra):

Such an elastic roller preferably has a surface roughness Ra of 0.05 μmor more and 2.5 μm or less. This is to make the agglutinated staineasily removable and, in the case of the developing roller, to maketoners easily transportable. As long as the elastic roller has a surfaceroughness of 0.05 μm or more, toner transport power is ensured, andghosts or density non-uniformity are inhibited from occurring in virtueof sufficient image density, to thereby obtain high-quality images. Aslong as the elastic roller has a surface roughness of 2.5 μm or less,the contact area with the adhesive roller is ensured to make theagglutinated stain readily removable.

In order to provide the elastic roller with such surface roughness, fineparticles having a volume average particle diameter of from 1 μm to 20μm may be dispersed therein. As such fine particles, the following maybe used: plastic pigments of fine polymethyl methacrylate particles,fine silicone rubber particles, fine polyurethane particles, finepolystyrene particles, fine amino resin particles or fine phenol resinparticles.

The surface roughness Ra may be defined by the value measured with acontact surface roughness meter SURFCOM 480A (manufactured by TokyoSeimitsu Co., Ltd.) according to the standard of JIS B 0601:1994 surfaceroughness. Specifically, using a stylus of 2 μm in radius, measurementis made at three spots in the peripheral direction for each of threespots in the axial direction (nine spots in total) under conditions of apressing pressure of 0.7 mN, a measuring rate of 0.3 mm/sec, a measuringmagnification of 5,000 times, a cut-off wavelength of 0.8 mm and ameasuring length of 2.5 mm. An average value of these is adopted as thesurface roughness Ra.

Hardness:

The hardness of the elastic roller may be selected in relation to thehardness of the pressing roller and adhesive roller, and is preferably20 degrees or more and 80 degrees or less in Asker-C hardness, and morepreferably 30 degrees or more and 70 degrees or less, in order to makethe agglutinated stain readily removable.

The size of the elastic roller may be selected in relation to thediameters of the pressing roller and adhesive roller, and is preferably4 mm or more and 200 mm or less in diameter in order to make theagglutinated stain readily removable.

Examples of such an elastic roller specifically include what are shownin FIGS. 1A and 1B. FIG. 1A is a sectional view of the elastic roller inits axial direction. FIG. 1B is a sectional view of the elastic rollerin the direction crossing at right angles to its axis. As shown in FIGS.1A and 1B, an elastic roller 20 has a mandrel 21 and provided thereon anelastic layer 22 and a surface layer 23 in this order formed on themandrel 22. The elastic layer and the surface layer may have not only asingle-layer structure but also a multi-layer structure.

Next, the regenerated elastic roller manufacturing process according tothe present invention is described in detail.

Step (1)

The step (1) in the regenerated elastic roller manufacturing processaccording to the present invention is a step of pressing a pressingroller against the elastic roller to apply pressure thereto. Thereby,the elastic roller is deformed locally to crack the agglutinated stainwhich has hardness high enough not to follow such deformation.

Thus, the adhesive force of the agglutinated stain to the elastic rolleris made lower than the adhesive force of the agglutinated stain to theadhesive roller.

Herein, as defined previously, the “cracks” refer to cracks of theagglutinated stain that are not seen before passing through the step(1), but are seen after passing through the step (1), when theagglutinated stain on the elastic roller surface is observed with ascanning electron microscope (SEM) at 5,000 magnifications.

According to studies made by the present inventors, cracking theagglutinated stain on the elastic roller in this way has been found tobe very important in removing the agglutinated stain in the step oftransfer the agglutinated stain to the surface of the adhesive rolleraccording to the step (2).

The pressing roller used in the step (1) preferably has an elastic layeron the periphery of a mandrel.

It is preferable for the mandrel of the pressing roller to have strengthhigh enough to be durable to the pressure at which a load is repeatedlyapplied to the elastic roller. The mandrel may be composed of metal orplastics. The material of the mandrel includes the same materials asexemplified for the elastic roller.

The elastic layer of the pressing roller presses and deforms the elasticroller surface. The material thereof may be a metallic, plastic orrubber material, but a relatively high-hardness rubber material ispreferred which can efficiently break the agglutinated stain of toner onthe surface without damaging the elastic roller surface. Specifically,it may include natural rubber, isoprene rubber, styrene rubber, butylrubber, butadiene rubber, fluororubber, urethane rubber and siliconerubber.

In order to efficiently break the agglutinated stain of toner on theelastic roller surface, the pressing roller preferably has hardnesshigher than the hardness of the elastic roller so as to press and deformthe elastic roller. Specifically, it is preferable that the pressingroller has an Asker-C hardness of 40 degrees or more and 90 degrees orless.

In order to efficiently break the agglutinated stain of toner on theelastic roller surface, the pressing roller preferably has surfaceroughness Ra which is set to be as large as possible in a range in whichthe elastic roller is not damaged. Specifically, the surface roughnessRa of the pressing roller is 0.1 μm or more and 5 μm or less.

The surface roughness Ra of the pressing roller can be brought into thedesired value by sanding the surface by means of a cylindrical sanderwhile controlling its sanding time. It is also effective that fineparticles having a volume average particle diameter of from 1 μm to 20μm are dispersed in the pressing roller. Such fine particles include thesame fine particles as exemplified for the elastic roller describedabove.

In order to efficiently break the agglutinated stain on the elasticroller surface, the pressing roller preferably has a diameter smallerthan the diameter of the elastic roller so as to increase the pressureat which a load is applied to the elastic roller. Specifically, thepressing roller preferably has a diameter of 1 mm or more and 10 mm orless.

In the step (1), the pressure at which the pressing roller is pressedagainst the elastic roller to apply a load thereto is preferably 10 N/mor more and 5,000 N/m or less, and particularly preferably 100 N/m ormore and 3,000 N/m or less, in drawing pressure.

As long as the drawing pressure at which a load is applied to theelastic roller is 10 N/m or more, the agglutinated stain of a developerorigin on the elastic roller surface can efficiently be broken. As longas the drawing pressure is 5,000 N/m or less, the elastic roller can bekept from being damaged at the time of pressing in the step (1).

Herein, the drawing pressure may be measured by the following method. ASUS stainless steel sheet of 30 μm in thickness to be drawn isinterposed between two SUS stainless steel sheets of 30 μm in thickness,and these are inserted into the contact part where the pressing rollerand the elastic roller are brought into contact with each other. Next,the SUS stainless steel sheet to be drawn is pulled, where the force ofdrawing at a rate of about 0.5 cm/sec is measured. The valuecorresponding to linear pressure converted into force per 1 m of thewidth of the SUS stainless steel sheet is defined as the drawingpressure.

The force of drawing is measured with a digital force gauge (trade name:DS2, manufactured by IMADA Co., Ltd.).

An example of such a pressing roller specifically includes what is shownin FIGS. 2A and 2B. FIG. 2A is a schematic sectional view of thepressing roller in its axial direction. FIG. 2B is a schematic sectionalview of the pressing roller in the direction crossing at right angles toits axis. As shown in FIGS. 2A and 2B, a pressing roller 40 has amandrel 41 and an elastic layer 42 thereon. The elastic layer may havenot only a single-layer structure but also one a multi-layer structure.

In the step (1) according to the present invention, as factors thatshould be controlled in order to crack the agglutinated stain of adeveloper origin on the elastic roller surface, the following are cited:

(i) the hardness of the elastic roller, (ii) the hardness of thepressing roller, (iii) the surface roughness Ra of the pressing roller,(iv) the force at which the pressing roller is pressed against theelastic roller and also (v) the relationship between the diameter of theelastic roller and the diameter of the pressing roller. Here, as to thefactor (v), it follows that the shape of a nip between the elasticroller and the pressing roller is defined, and hence the factor (v) isconsidered to be concerned with occurrence of cracks.

Then, the factors (i) to (iv) are appropriately controlled within thenumerical ranges as described above, and the factor (v) is set tosatisfy Db<Da (Da: diameter of elastic roller; Db: diameter of pressingroller) as detailed later, and thereby, the agglutinated stain can becracked.

Step (2)

The step (2) in the regenerated elastic roller manufacturing process ofthe present invention is a step in which an adhesive roller having anadhesive layer on its surface is brought into contact with the elasticroller to adhere the agglutinated stain of a developer origin that hasbeen cracked in the step (1) to the surface of the adhesive roller, tothereby remove the agglutinated stain of toner from the surface of theelastic roller.

The adhesive roller used in the step (2) is a roller having an adhesiveproperty of adhering the agglutinated stain of a developer origin on theelastic roller surface. The adhesive roller preferably has elasticity inorder to improve the effect of removing the agglutinated stain of adeveloper origin. The adhesive roller preferably has an adhesive layerwith elasticity on the periphery of the mandrel.

It is preferable for the mandrel of the adhesive roller to have strengthhigh enough to be durable to the stress under which the adhesive rolleris repeatedly brought into contact with the elastic roller. The materialof the mandrel includes metals and plastics. Specifically, the materialincludes the same materials as exemplified for the elastic roller.

In the adhesive layer of the adhesive roller, a polymeric material suchas rubbers or elastomer having elasticity may be used as a base materialto reduce hardness, to thereby generate an adhesive property togetherwith the elasticity. Preferably, that layer is further incorporated withan adhesion-providing resin which provides the layer with an adhesiveproperty. The adhesive property of the adhesive roller may be controlledby changing the content of such an adhesion-providing resin.

Examples of the polymeric material of the base material include naturalrubber, isoprene rubber, styrene rubber, butyl rubber, butadiene rubber,ethylene-propylene rubber, fluororubber, urethane rubber, siliconerubber, and combinations of two or more selected from these. Of these,non-polar rubbers such as natural rubber, isoprene rubber, styrenerubber, butyl rubber, butadiene rubber, ethylene-propylene rubber andsilicone rubber are preferred because they have durability for theelasticity and the adhesive property. In particular, non-polar rubbers,such as isoprene rubber and butyl rubber, containing an isoprenestructure are preferred. This is because they have durability to organicsolvents in addition to the elasticity and the adhesive property. Hence,the toner adhered to the surface of the adhesive roller can easily beremoved by the use of an organic solvent and the roller can repeatedlybe used.

Examples of the adhesion-providing resin include the following:

Terpene type adhesion-providing resins such as terpene phenol resin,aromatic modified terpene resin, hydrogenated terpene resin and liquidterpene resin; pinene type resins such as α-pinene resin and β-pineneresin; rosin and rosin derivatives; petroleum resins; and mixtures oftwo or more selected from the above.

The adhesive layer of the adhesive roller preferably includes thenon-polar rubber containing an isoprene structure and the terpene typeadhesion-providing resin. As having such an adhesive layer, the adhesiveroller can maintain its elasticity and adhesion over a longer periodtime, and the adhesive force can easily be regenerated, and thus, thenumber of the regenerated elastic rollers to be produced can beincreased.

The adhesive layer of the adhesive roller is in a thickness of from 1 mmor more and 50 mm or less.

Such an adhesive roller is commercially designated as CLEAN DASH ROLLER(trade name; manufactured by Techno Roll Co., Ltd.).

The adhesive roller may have an elastic layer and the adhesive layerformed thereon.

The adhesive roller preferably has the adhesive force within the rangeof 0.2 N/cm or more and 20 N/cm or less. As long as the adhesive rollerhas an adhesive force of 0.2 N/cm or more, it can adhere theagglutinated stain of toner cracked on the elastic roller surface toeffectively remove the agglutinated stain from the elastic roller. Aslong as the adhesive roller has an adhesive force of 20 N/cm or less, itdoes not damage the elastic roller surface when peeling off theagglutinated stain, and besides, when peelings or breakages occur in theadhesive roller itself, they can be inhibited from adhering to theelastic roller surface. The adhesive force of the adhesive roller may becontrolled by appropriately selecting the types of base materials andadhesion-providing resins used in the adhesive layer and varying thecontent of the adhesion-providing resin.

Herein, the adhesive force of the adhesive roller can be defined by thevalue measured according to JIS Z 0237. A sheet made from the materialof the resin layer of the elastic roller is used in place of a SUS304steel sheet prescribed in JIS Z 0237, and is laminated to the adhesiveroller. This is left standing for 1 hour at a temperature of 23° C. anda humidity of 50% RH. Thereafter, using a Tensilon type tensile tester,the sheet is torn off in the direction of 180° at a tensile rate of 300mm/minute, where the maximum tensile force (N/cm) is defined as theadhesive force.

The sheet used as the resin layer of the elastic roller, used inmeasuring the adhesive force, may be made from a material describedbelow.

First, the following materials are each mixed with methyl ethyl ketone(MEK).

-   -   Polytetramethylene glycol (trade name: PTG100SN; molecular        weight Mn: 1,000, f: 2, where f represents the number of        functional groups; available from Hodogaya Chemical Co., Ltd.):        100 parts by mass.    -   Isocyanate (trade name: MILLIONATE MT; MDI, f: 2; available from        Nippon Polyurethane Industry Co., Ltd.): 21.2 parts by mass.

Then, the mixture obtained is allowed to react at a temperature of 80°C. for 6 hours in an atmosphere of nitrogen to produce a bifunctionalpolyurethane polyol prepolymer having a molecular weight Mw of 48,000, ahydroxyl value of 5.6, and a degree of molecular weight dispersion Mw/Mnof 2.9 and Mz/Mw of 2.5.

Next, 100 parts by mass of the polyurethane polyol prepolymer and 7.2parts by mass of an isocyanate (trade name: TAKENATE B830; TMP modifiedTDI, f (the number of functional groups): equivalent to 3; availablefrom Mitsui Takeda Chemicals, Inc.) are mixed to prepare a raw-materialsolution of 1.2 in NCO equivalent weight. A wet coating of thisraw-material solution is heat-cured to produce the sheet.

It is preferable that the adhesive roller has hardness smaller than thatof the elastic roller. This is because the contact area with the elasticroller can be made larger and also the agglutinated stain of toner canbe easily adhered to the adhesive roller. For example, the adhesiveroller may have the Asker-C hardness of 10 degrees or more and 50degrees or less.

Further, the adhesive roller preferably has a diameter larger than thatof the elastic roller. This is because the contact area with the elasticroller can be made larger and the agglutinated stain of toner can beeasily adhered to the adhesive roller. For example, the adhesive rollermay have a diameter of 10 mm or more and 100 mm or less.

With use of the adhesive roller, the agglutinated stain of toner adheredto the adhesive roller surface increases in quantity. Accordingly, it ispreferable that adhesive roller is appropriately cleaned so that theagglutinated stain of toner can removed from the surface so as torestore the adhesive force. To restore the adhesive force of theadhesive roller, the adhesive roller may be wiped by using an organicsolvent that does not impair the adhesive force, to thereby remove theagglutinated stain of toner. The organic solvent that may be usedinclude methanol, ethanol, isopropyl alcohol, acetone, and methyl ethylketone. Such removal treatment can be carried out in such a state thatthe adhesive roller is detached.

Alternatively, an adhesive tape or another adhesive roller havingstronger adhesive force is brought into contact with the adhesive rollerto remove the agglutinated stain of toner from the adhesive roller.Moreover, a sheet member impregnated with an organic solvent may bepressed against the surface of the adhesive roller while being rotated,to thereby remove the agglutinated stain of toner without taking anydowntime.

An example of such an adhesive roller specifically includes what isshown in FIGS. 3A and 3B. FIG. 3A is a schematic sectional view of theadhesive roller in its axial direction. FIG. 3B is a schematic sectionalview of the adhesive roller in the direction crossing at right angles toits axis. As shown in FIGS. 3A and 3B, an adhesive roller 30 has amandrel 31 and an adhesive layer 32 formed thereon. The adhesive layer32 may have not only a single-layer structure but also a multi-layerstructure.

Steps (1) and (2)

Such steps (1) and (2) may be successively carried out, but maypreferably simultaneously be carried out on the upstream side and thedownstream side with respect to the elastic roller while being rotated.This is because the agglutinated stain on the elastic roller canefficiently be cracked in a shorter time and be removed therefrom.

Prior to the step (1), it is preferable to further provide a step inwhich the agglutinated stain of a developer origin on the elastic rollersurface is kept at a temperature of from −10° C. or more and 10° C. orless. This is because the agglutinated stain can be reduced inflexibility within a range in which its adhesion is not lowered, and canbe easily cracked through the step (1). A measure for keeping theagglutinated stain at the above temperature includes a method in which agas with a temperature kept within the above range is blown, or aworking atmosphere is kept within the above temperature range, so thatat least the outermost surface of the elastic roller can have the abovetemperature.

The elastic roller, the pressing roller and the adhesive roller may haveAsker-C hardnesses Ha, Hb and Hc, respectively, which preferably satisfya relationship of Hc<Ha<Hb. This is because the agglutinated stain canmore efficiently be removed.

That is, the rollers having the above relationship are considered to beadvantageous on the following points.

-   -   The point that the level of deformation of the elastic roller in        virtue of the pressing roller can be enlarged to efficiently        crack the agglutinated stain.    -   The point that the contact area between the adhesive roller and        the elastic roller can be enlarged to easily remove the        agglutinated stain from the elastic roller.

The elastic roller, the pressing roller and the adhesive roller may alsohave diameters Da, Db and Dc, respectively, which preferably satisfy arelationship of Db<Da<Dc. This is because the agglutinated stain canmore efficiently be removed. The rollers having such a relationship areadvantageous in the following points.

-   -   The point that the pressure at which the pressing roller is        pressed against the elastic roller to apply a load can be        enlarged to efficiently crack the agglutinated stain.    -   The point that the contact area between the adhesive roller and        the elastic roller can be enlarged to easily remove the        agglutinated stain from the elastic roller.

FIG. 4 is a schematic structural view showing an example of aregenerated elastic roller manufacturing unit used in the regeneratedelastic roller manufacturing process of the present invention. In aregenerated elastic roller manufacturing unit 10 shown in FIG. 4, anelastic roller 20 to be recovered is placed in a rotatable state. Apressing roller 40 is placed in a freely rotatable state while pressingthe elastic roller 20 at a certain pressure. The pressing roller 40deforms the agglutinated stain of a developer origin on the surface ofthe elastic roller at a nip with the elastic roller 20 to crack theagglutinated stain. An adhesive roller 30 is also placed in a freelyrotatable state while coming into contact with the elastic roller 20.The agglutinated stain of a developer origin cracked at the nip betweenthe elastic roller 20 and the pressing roller 40 adheres to the surfaceof the adhesive roller 30 and is removed from the surface of the elasticroller 20. The respective rollers are supported by supports (not shown).The respective supports are set up so that the distances between themare controllable. This makes nip pressure controllable between therespective rollers. The pressing roller 40 and the adhesive roller 30may be rotated following the elastic roller 20 rotated by a motor (notshown), or their mandrels may be connected with rotating shafts ofmotors so that the rotational speed can be controlled for each roller tomake their rotational directions selectable.

It is described below how such a regenerated elastic rollermanufacturing unit operates.

First, the elastic roller 20 to be recovered is placed at apredetermined position. The pressing roller 40 is also so placed as toapply a pressure of 500 N/m in drawing pressure to the elastic roller20.

Next, the rotational speed of the elastic roller is set at, e.g., 5 to300 rpm taking into account the removal efficiency of the agglutinatedstain of toner. Here, the rotational speeds of the adhesive roller 30and the pressing roller 40 may be so set as to produce a difference inperipheral speed with respect to the elastic roller 20. Making theserollers have different rotational speeds enables the agglutinated stainto be efficiently broken and removed by utilizing the effect of rubbing.

The elastic roller 20, the adhesive roller 30 and the pressing roller 40are rotated to carry out processing for a time sufficient for theremoval of the agglutinated stain, e.g., for 5 to 120 seconds. Theagglutinated stain cracked is adhered to the adhesive roller surface,and thus removed from the surface of the elastic roller 20. Thereafter,the rotational drive is stopped, and the elastic roller having beenrecovered is taken out.

FIG. 5 is a schematic structural view showing another example of theregenerated elastic roller manufacturing unit according to the presentinvention. The regenerated elastic roller manufacturing unit shown inFIG. 5 is set up by providing the regenerated elastic rollermanufacturing unit shown in FIG. 4 with a cleaning member 50 for theadhesive roller 30. The cleaning member 50 is a sheet member impregnatedwith an organic solvent. The sheet member 50 is brought into pressuretouch with the adhesive roller 30, and in this state, is so driven as tosupply its fresh surface as the adhesive roller is rotated. Theagglutinated stain of a developer origin adhered to the surface of theadhesive roller 30 from the elastic roller 20 being rotated furthermoves to the sheet member 50, where the surface of the adhesive roller30 is cleaned. Hence, the agglutinated stain can be removed from theelastic roller 20 repeatedly over a long period of time.

FIG. 6 is a schematic structural view showing still another example ofthe regenerated elastic roller manufacturing unit according to thepresent invention. The regenerated elastic roller manufacturing unitshown in FIG. 6 is provided with a cleaning roller 60 having a strongadhesive force as a cleaning member for the adhesive roller. Thecleaning roller 60 is set up in such a state that it is in pressuretouch with the adhesive roller 30. Then, the cleaning roller is drivenso that the agglutinated stain adhered to the surface of the adhesiveroller 30 may be transferred to the cleaning roller 60 as the adhesiveroller 30 is rotated. The agglutinated stain adhered to the surface ofthe adhesive roller 30 from the elastic roller 20 being rotated furthermoves to the surface of the cleaning roller 60, thus the surface of theadhesive roller 30 is cleaned. As a result, the agglutinated stain canbe removed from the elastic roller 20 repeatedly over a long period oftime.

The regenerated elastic roller obtained by the above regenerated elasticroller manufacturing process can be reused as the developing roller,charging roller, transfer roller, fixing roller or cleaning roller foruse in image forming apparatuses utilizing an electrophotographicprocess. In particular, it is suitable for use in the developing roller.

The electrophotographic image forming apparatus according to the presentinvention has a charging member which charges a photosensitive memberand a developing member which develops an electrostatic latent imageheld on the photosensitive member, and is provided with the aboveregenerated elastic roller.

FIG. 7 is a schematic sectional view showing an example of such anelectrophotographic image forming apparatus. The electrophotographicimage forming apparatus shown in FIG. 7 is provided with aphotosensitive drum 701, a charging roller 702, and laser light 703 asan exposure means by which electrostatic latent images are written onthe photosensitive drum 701.

The apparatus is provided with a developing assembly R which developsinto toner images the electrostatic latent images held on thephotosensitive drum surface, and a transfer roller 708 which transfersthe toner images to a recording medium 707 such as paper fed by means ofa paper feed roller 706. A fixing roller 709 is further provided whichfixes the toner images transferred to the recording medium by the aid ofpressure applied by a pressure roller 710. After image formation hasbeen completed, the recording medium to which the toner images have beenfixed is so set as to be delivered out of the apparatus.

The apparatus is provided with a cleaning blade 711 with which thedeveloper remaining on the photosensitive drum 701 without beingtransferred is removed as the photosensitive drum is rotated, to cleanits surface, a waste toner container 712 in which the toner scraped offfrom the photosensitive drum surface is collected, and so forth. Thephotosensitive drum from which such residual toner has been removed isso set as to stand by for next image formation. A cleaning roller may beused in place of the cleaning blade 711.

The developing assembly R is provided with a developer container 714which holds a developer 705 therein, a developing roller 704, adeveloper feed roller 713, a developer control blade 715, an agitatingblade and so forth. The developing roller is so placed as to close anopening of the developer container and face the photosensitive drum atits part uncovered from the developer container. To this developingroller, the regenerated elastic roller described above is applied.

Four electrophotographic process cartridges containing black, magenta,cyan and yellow developers, respectively, may be arranged and theirrespective toner images formed may be transferred and fixed to arecording medium, to thereby produce a color image-formed matter.

The regenerated elastic roller described above may also be applied tothe above charging roller, fixing roller, pressure roller, developerfeed roller, cleaning roller, paper feed roller, transfer roller and sofroth.

In such an image forming apparatus, the photosensitive drum 701 rotatedin the direction of an arrow A is charge-processed on its surface by thecharging roller 702 so as to be provided with uniform potential with apredetermined polarity. Thereafter, the photosensitive drum 701 thuscharged is exposed to exposure light 703 according to objective imageinformation, where electrostatic latent images corresponding toobjective images are formed on the surface of the photosensitive drum701. The electrostatic latent images are rendered visible as tonerimages by means of the developer 705 fed by the developing roller 704rotated in the direction of an arrow B. The toner images formed byrendering the latent images visible are transferred to the recordingmedium 707 by the aid of voltage applied by the transfer roller 708 fromthe back side of the recording medium 707 fed by the paper feed roller706, and this recording medium 707 with the toner images is transportedto the part between the fixing roller 709 and the pressure roller 710,where the toner images are fixed to produce an image-formed matter. Thephotosensitive drum 701 is cleaned with the cleaning blade 711 in orderto remove the toner and dust which remain thereon, then de-charged bymeans of a charge-eliminating member (not shown) and again proceeds withthe charging step. The toner removed by the cleaning blade 711 iscollected in a waste toner container 712.

In the developer container, the developer sent to the developer feedroller by the aid of the agitating blade is uniformly applied on thedeveloping roller surface by means of the developer control blade.Subsequently, it is transported to the photosensitive drum as thedeveloping roller is rotated. Then, it is transferred onto electrostaticlatent images to develop the electrostatic latent images.

The developer remaining on the developing roller without being used forthe development of electrostatic latent images is transported into thedeveloper container as the developing roller is rotated, and is scrapedoff by the developer feed roller in the developer container, where, atthe same time, the developer is anew fed to the developing roller.

The electrophotographic process cartridge of the present invention has aphotosensitive member on which an electrostatic latent image is to beformed, a charging member which charges the photosensitive member and adeveloping member which develops the electrostatic latent image held onthe photosensitive member, and is so set up as to be detachablymountable to the main body of an electrophotographic image formingapparatus. It further has the regenerated elastic roller according tothe present invention as at least one of the charging member and thedeveloping member.

It is only required for the electrophotographic process cartridge tohave the photosensitive member, the charging member and the developingmember and to be detachably mountable to the main body of anelectrophotographic image forming apparatus. As an example of theelectrophotographic process cartridge, the following may be cited: aprocess cartridge which has, in the image forming apparatus shown inFIG. 7, the charging roller 702, the photosensitive drum 701 and thedeveloping roller 704 in an integral form and is detachably mountable tothe main body of an electrophotographic image forming apparatus. Theprocess cartridge may further have the developer feed roller 713, thedeveloper control blade 715 and the agitating blade, and also at leastone of the developer container holding the developer therein, thetransfer roller, the cleaning roller and so froth, which are supportedin an integral form.

EXAMPLES

The regenerated elastic roller, electrophotographic process cartridgeand electrophotographic image forming apparatus of the present inventionare specifically described below in detail. The technical scope of thepresent invention is by no means limited by these. In the following,“part(s)” refers to “parts by mass” unless particularly noted.

Example 1 Production of Elastic Roller (A-1)

As a mandrel, a mandrel made of SUS stainless steel was used to theouter periphery of which an adhesive was applied, and was then baked.

As a material for an elastic layer, a liquid silicone rubber wasprepared in the following way.

First, the following materials were mixed to prepare a base material forthe liquid silicone rubber.

-   -   Dimethyl polysiloxane having a viscosity of 100 Pa·s, which have        been substituted with vinyl groups at both ends: 100 parts by        mass.    -   Quartz powder (Min-USil, available from Pennsylvania Glass Sand        Corporation) as filler: 7 parts by mass.    -   Carbon black (DENKA BLACK, a powdery product, available from        Denki Kagaku Kogyo Kabushiki Kaisha): 8 parts by mass.

The base material obtained was divided into two portions. A platinumcompound was mixed in one of them as a curing catalyst in tracequantity, and 3 parts by mass of an organohydrogenpolysiloxane was mixedin the other. These mixtures were mixed in a mass ratio of 1:1 toprepare the liquid silicone rubber.

The mandrel was placed at the center of a cylindrical mold, where theliquid silicone rubber was poured into the cylindrical mold through itsfill opening, and was heat-cured at a temperature of 120° C. for 5minutes. The molded product was cooled and thereafter demolded. This wasfurther heated at a temperature of 200° C. for 4 hours to completecuring reaction. Thus, an elastic layer of about 4 mm in thickness wasprovided on the outer periphery of the mandrel.

Next, the following materials were stepwise introduced in methyl ethylketone.

-   -   Polytetramethylene glycol (trade name: PTG1000SN; molecular        weight Mn: 1,000, f: 2, where f represents the number of        functional groups; available from Hodogaya Chemical Co., Ltd.):        100 parts by mass.    -   Isocyanate (trade name: MILLIONATE MT; MDI, f: 2; available from        Nippon Polyurethane Industry Co., Ltd.): 21.2 parts by mass.

The mixture obtained was allowed to react at a temperature of 80° C. for6 hours in an atmosphere of nitrogen to produce a bifunctionalpolyurethane polyol prepolymer having a molecular weight Mw of 48,000, ahydroxyl value of 5.6, and a degree of molecular weight dispersion Mw/Mnof 2.9 and Mz/Mw of 2.5.

100 parts by mass of this polyurethane polyol prepolymer and 7.2 partsby mass of an isocyanate (trade name: TAKENATE B830; TMP modified TDI, f(the number of functional groups): equivalent to 3; available fromMitsui Takeda Chemicals, Inc.) were mixed so as to be 1.2 in NCOequivalent weight. Further, 20 parts by mass of carbon black (#1000; pH:3.0; available from Mitsubishi Chemical Corporation) was added toprepare a liquid raw-material mixture.

To the liquid raw-material mixture, methyl ethyl ketone was added toadjust its solid content to 25% by mass. Further, 30 parts by mass ofurethane resin particles (trade name: C400 Transparent; particlediameter: 14 μm; available from Negami Chemical Industrial Co., Ltd.)were added, followed by uniform dispersion and mixing to prepare acoating fluid for surface layer formation.

Using this coating fluid, a surface layer was formed by a dipping methodon the elastic layer formed on the outer periphery of the mandrel.Specifically, the coating fluid, which was kept at a liquid temperatureof 23° C., was poured into a cylinder of 32 mm in inner diameter and 300mm in length from its bottom in an amount of 250 cc per minute, and thecoating fluid having overflowed from the upper end of the cylinder wasagain poured into the cylinder from its bottom so as to be circulated.The elastic layer formed on the outer periphery of the mandrel wasdipped into the coating fluid in the cylinder at a dipping rate of 100mm/s, was then stopped for 10 seconds, and thereafter drawn up underconditions of an initial rate of 300 mm/s and a final rate of 200 mm/s.The wet coating formed was naturally dried for 60 minutes.

Then, the coating dried was heat-treated at 140° C. for 60 minutes toeffect curing to form a surface layer of 15 μm in thickness and 1.0 μmin surface roughness Ra on the outer periphery of the elastic layer. Theelastic roller (A-1) thus obtained was 16 mm in outer diameter and 45degrees in Asker-C hardness.

Formation of agglutinated stain of developer origin:

The elastic roller (A-1) was employed as a developing roller in anelectrophotographic process cartridge for an electrophotographic imageforming apparatus (trade name: Color Laser Jet 4700dn, manufactured byHP Ltd.). This was left standing for 24 hours in an environment of atemperature of 15° C. and a humidity of 10% RH. Thereafter, thiselectrophotographic process cartridge was mounted to the main body ofthe electrophotographic image forming apparatus, and in the environmentof a temperature of 15° C. and a humidity of 10% RH, images of 1% inprint percentage were reproduced until the remaining amount of thedeveloper came to be 20 g, to thereby adhere the agglutinated stain of adeveloper origin to the developing roller surface.

Next, the developing roller was detached from the electrophotographicprocess cartridge, and then air was blown against the surface of thedeveloping roller to blow off developer components on the developingroller surface. Thereafter, the developing roller surface was observedwith a scanning electron microscope at 5,000 magnifications to find thatcomponents of a developer origin were adhered much to the rollersurface. The surface of the agglutinated stain was seen not to crack.

Production of Adhesive Roller (C-1)

A mandrel was readied which was a mandrel made of SUS stainless steel tothe outer periphery of which an adhesive was applied.

A mixture of the following materials was extruded into a tube by meansof an extruder, followed by vulcanization at 140° C. for 30 minutes in avulcanizer to produce a tubular extruded product.

-   -   Butyl rubber: 100 parts by mass.    -   Quartz powder (Min-USil, available from Pennsylvania Glass Sand        Corporation) as filler: 5 parts by mass.    -   Terpene phenol resin (YS POLYSTAR U, available from Yasuhara        Chemical Co., Ltd.): 20 parts by mass.

To this tubular extruded product, the mandrel readied previously waspress-fitted and bonded. Further, the surface of the resulting productwas ground by means of a cylindrical grinder to obtain an adhesiveroller of 50 mm in diameter and 30 degrees in Asker-C hardness. Theadhesive force of this adhesive roller was 5 N/cm. The adhesive rollerwas used after being appropriately cleaned with an organic solvent so asto restore the adhesive force.

Production of Pressing Roller (B-1)

A mandrel was readied which was a mandrel made of SUS stainless steel tothe outer periphery of which an adhesive was applied.

A mixture of the following materials was extruded into a tube by meansof an extruder, followed by vulcanization at 140° C. for 30 minutes in avulcanizer to obtain a tubular extruded product having the desired outerdiameter.

-   -   Butyl rubber (Butyl 1065,available from Japan Butyl Co., Ltd.):        100 parts by mass.    -   Quartz powder (Min-USil, available from Pennsylvania Glass Sand        Corporation) as filler: 15 parts by mass.

To this tubular extruded product, the mandrel readied previously waspress-fitted and bonded. Further, The surface of the resulting productwas ground by means of a cylindrical grinder to produce a pressingroller of 0.1 μm in surface roughness Ra, 8 mm in diameter and 60degrees in Asker-C hardness.

The elastic roller (A-1) on which a layer composed of the agglutinatedstain of a developer origin was formed, the pressing roller (B-1) andthe adhesive roller (C-1) were set in the regenerated elastic rollermanufacturing unit shown in FIG. 4. In the step (1), the pressure atwhich the pressing roller was pressed against the elastic roller was setat 500 N/m in drawing pressure. In an atmosphere of normal temperature,the elastic roller was rotated at 60 rpm, and the pressing roller andthe adhesive roller were rotated for 30 second following the elasticroller to produce a regenerated elastic roller.

The elastic roller surface having passed through the step (1) wasobserved with a scanning electron microscope (trade name: FE-SEM4700,manufactured by Hitachi Ltd.) at 5,000 magnifications. As a result, theagglutinated stain on the elastic roller surface was found to havecracks which were not seen before passing through the step (1). Thesurface of the regenerated elastic roller produced through the steps (1)and (2) was also observed with the scanning electron microscope at 5,000magnifications to find that any agglutinated stain was not seen to bepresent. This regenerated elastic roller was used in image formation inthe following way, and was evaluated for the quality as a regeneratedelastic roller.

Image Formation & Image Evaluation

—Evaluation—

Evaluation on Ghosts:

The regenerated elastic roller of this Example was set as a developingroller in an electrophotographic process cartridge for anelectrophotographic image forming apparatus (trade name: Color Laser Jet4700dn; manufactured by HP Ltd.). This electrophotographic processcartridge was left standing for 24 hours in an environment of atemperature of 15° C. and a humidity of 10% RH. Thereafter, theelectrophotographic process cartridge was mounted to the main body ofthe electrophotographic image forming apparatus. In the environment of atemperature of 15° C. and a humidity of 10% RH, images in which solidblack images of 15 mm×15 mm were printed at intervals of 15 mm in ahorizontal line in the upper region of the images, and further, ahalftone image was printed in the lower region of the images werereproduced as images for evaluation on ghosts.

If images are formed by using a developing roller on the surface ofwhich the agglutinated stain of toner has been much formed, the chargequantity of toner on the developing roller becomes short. If images areformed in this state, the toner is insufficiently scraped off by thetoner feed roller, and development residual toner remains on thedeveloping roller without being replaced. As a result, due to thedifference in development efficiency between areas solid-developed andareas not done, patch patters appear in the halftone region indeveloping roller cycles. This is called ghosts. The level of ghosts canbe used as an index of how far the contamination of surface has beeneliminated as a result of the regeneration processing.

On ghosts appearing in the halftone region of the images reproduced,evaluation was made according to the following criteria.

A: No ghosts are visually seen at all.

B: Ghosts are slightly seen.

C: Ghosts are seen in which even corners are viewable.

D: Ghosts further come about over many cycles in developing rollerrotation.

Evaluation on Fogging:

After the evaluation on ghosts, white solid images were furtherreproduced, and the extent of fogging (fogging value) was measured inthe following way.

Reflection density of a transfer sheet before image formation andreflection density of the transfer sheet after image formation of solidwhite images were measured with a reflection densitometer (trade name:TC-6DS/A, manufactured by Tokyo Denshoku Technical Center Company Ltd.),and the difference between them was defined as the fogging value of thedeveloping roller.

The whole of the image-printed regions of the transfer sheet werescanned to measure the reflection density, and the minimum value thereofwas regarded as the reflection density of the transfer sheet.

When white solid images are formed by using a developing roller on thesurface of which the agglutinated stain is much formed, toner short incharge quantity moves onto the photosensitive member. Further, thistoner is transferred onto the transfer sheet to bring about fogging.Accordingly, the fogging value may be used as an index of how far theagglutinated stain on the surface of the regenerated elastic roller hasbeen removed.

On the fogging value, evaluation was made according to the followingcriteria. It is considered that the smaller the fogging value is, themore the agglutinated stain on the roller surface has been removed.Here, the following evaluation A and evaluation B indicate levels atwhich “fogging” is not visually detected. On the other hand, evaluationC and evaluation D indicate levels at which “fogging” is visuallyclearly detected.

A: The value is smaller than 1.0.

B: The value is 1.0 or more and smaller than 2.0.

C: The value is 3.0 or more and smaller than 5.0.

D: The value is 5.0 or more.

Comparative Example 1

The elastic roller (A-1) with the agglutinated stain formed thereon wasused as it was, without being subjected to regeneration processing, forthe same experiments on image formation and image evaluation as inExample 1. Ghosts and fogging of the images obtained were evaluatedaccording to the above criteria. The results obtained are shown in Table1.

Comparative Example 2

The elastic roller (A-1) with the agglutinated stain formed thereon wassubjected to regeneration processing in the same way as in Example 1except that the pressing roller (B-1) was not placed. The surface of theregenerated elastic roller obtained was observed with a scanningelectron microscope (trade name: FE-SEM4700, manufactured by HitachiLtd.) at 5,000 magnifications. As a result, any agglutinated stain wasunable to be seen. Next, this regenerated elastic roller was used forthe same experiments on image formation and image evaluation as inExample 1. The images obtained were evaluated according to the samecriteria as in Example 1. The results obtained are shown in Table 1.

TABLE 1 Step(s) of regeneration processing carried out Ghosts FoggingExample 1 First & second steps A A Comparative Not carried out C DExample 1 Comparative Second step only B C Example 2

From the results shown in Table 1 above, it is seen that the regeneratedelastic roller obtained through the steps (1) and (2) has had theagglutinated stain removed from its surface, can improve image qualityat a level high enough for the roller to be reusable and can be used asa developing roller. From the results of Comparative Example 2, it isascertainable that the agglutinated stain on the elastic roller surfacecan be removed in appearance even by the use of only the adhesiveroller, but the roller is clearly difference in quality from theregenerated elastic roller in Example 1 when being used in theelectrophotographic image forming apparatus.

Example 2 Elastic Roller

Two types of elastic rollers (A-2-1 and A-2-2) were produced in the sameway as in Example 1 except that the quartz powder to be contained asfiller in the elastic layer was mixed in amounts of 2 parts by mass and20 parts by mass, respectively. The elastic rollers were degrees and 70degrees in Asker-C hardness, respectively.

Pressing Roller:

Three types of pressing rollers (B-2-1, B-2-2 and B-2-3) were producedin the same way as in Example 1 except that the quartz powder was mixedin amounts of 8 parts by mass, 10 parts by mass and 25 parts by mass,respectively. The pressing rollers were 45 degrees, 50 degrees and 80degrees in Asker-C hardness, respectively.

Adhesive Roller:

Four types of adhesive rollers (C-2-1, C-2-2, C-2-3 and C-2-4) wereproduced in the same way as in Example 1 except that the quartz powderwas mixed in amounts of 0 parts by mass, 4 parts by mass, 6 parts bymass and 8 parts by mass, respectively. The adhesive rollers were 20degrees, 40 degrees, 45 degrees and 50 degrees in Asker-C hardness,respectively.

Regenerated elastic rollers were produced in the same way as in Example1 except that the elastic roller, the pressing roller and the adhesiveroller were used in combination as shown in Table 2 below. Then, theregenerated elastic rollers obtained were evaluated in the same way asin Example 1. The results are shown together in Table 2.

TABLE 2 Aggluti- nated stain with or Elastic Pressing Adhesive withoutFog- Example: roller roller roller cracks Ghosts ging 2-1 A-1 B-2-1C-2-3 with B B 2-2 A-1 B-2-1 C-1 with A B 2-3 A-1 B-1 C-2-3 with B B 2-4A-1 B-1 C-1 with A A 2-5 A-1 B-2-2 C-2-2 with A A 2-6 A-2-1 B-2-2 C-2-1with A A 2-7 A-2-2 B-2-3 C-2-4 with A A

It is seen from the above results that in Examples 2-1 to 2-7, theregenerated elastic rollers have had the agglutinated stain of tonerremoved from their surfaces, can improve image quality at a level highenough for the rollers to be reusable and can be used as developingrollers. It is also seen that the image quality is especially good inExamples 2-4 to 2-7 in which the relationship of Hc<Ha<Hb is satisfiedwhere Ha, Hb and Hc represent Asker-C hardnesses of the elastic roller,pressing roller and adhesive roller, respectively.

Example 3

The procedure described in Example 1 was repeated to produce the elasticroller A-1, the pressing roller B-1 and the adhesive roller C-1.

An elastic roller A-3-1 was also produced in the same way as in theelastic roller A-1 in Example 1 except that the thickness of the elasticlayer was so changed as to be 12 mm.

Pressing rollers (B-3-1, B-3-2 and B-3-3) were produced in the same wayas in the pressing roller in Example 1 except that they were 10 mm, 14mm and 16 mm in diameter, respectively.

Adhesive rollers (C-3-1, C-3-2 and C-3-3) were produced in the same wayas in Example 1 except that they were 14 mm, 16 mm and 18 mm indiameter, respectively.

Regenerated elastic rollers were produced in the same way as in Example1 except that these rollers in were used in combination as shown inTable 3 below. Images were formed using the regenerated elastic rollersas developing rollers to make an evaluation. In this Example, evaluationwas also made on how far the agglutinated stain of a developer origin onthe elastic roller surface was cracked. To make the evaluation, thesurfaces of elastic rollers having passed through only the step (1) wereobserved on a scanning electron microscope (trade name: FE-SEM4700,manufactured by Hitachi Ltd.) at 5,000 magnifications, where the extentof cracks seen on the agglutinated stain surface within the range of 50μm×50 μm in area was evaluated according to the following criteria. Itis considered that as the agglutinated stain is increasingly divided bycracks, the agglutinated stain is more easily removed by the adhesiveroller.

A: The agglutinated stain is entirely cracked and finely divided.

B: The agglutinated stain is entirely cracked and partially finelydivided.

The results of this Example are shown together in Table 3 below.

TABLE 3 Elastic Pressing Adhesive Extent Fog- Example: roller rollerroller of cracks Ghosts ging 3-1 A-1 B-3-3 C-3-2 B B B 3-2 A-1 B-3-3 C-1B A B 3-3 A-1 B-1 C-3-2 A B B 3-4 A-1 B-1 C-1 A A A 3-5 A-1 B-3-2 C-3-3A A A 3-6 A-3-1 B-3-1 C-3-1 A A A 3-7 A-3-1 B-1 C-1 A A A

As shown in Table 3, in Examples 3-1 to 3-7, the regenerated elasticrollers have had the agglutinated stain removed from their surfaces, canimprove image quality at a level high enough for the rollers to bereusable and can be used as developing rollers. Further, the imagequality can be more improved in Examples 3-4 to 3-7 in which therelationship of Db<Da<Dc is satisfied where Da, Db and Dc represent thediameters of the elastic roller, pressing roller and adhesive roller,respectively. The reason for the above is presumed to be due to the factthat the agglutinated stain is more finely divided in Examples 3-4 to3-7 than in Examples 3-1 to 3-3.

Example 4

In the same way as in Example 1 except that the pressure at which thepressing roller was pressed against the elastic roller (drawingpressure) was changed as shown in Table 4, thirty regenerated elasticrollers were produced for each pressure. Visual observations were madefor the thirty regenerated elastic rollers on whether or not theirsurfaces were scratched due to pressing with the pressing roller. Allthe regenerated elastic rollers were also evaluated in the same way asin Example 1. The results obtained are shown in Table 4.

TABLE 4 Drawing Agglutinated Surface with pressure stain with or orwithout Example: (N/m) without cracks Ghosts Fogging scratches 4-1 50with B B without 4-2 100 with A A without 4-3 500 with A A without 4-43,000 with A A without

As shown in Table 4, in Examples 4-1 to 4-5, the agglutinated stain onthe roller surface can be removed to the extent that the regeneratedelastic rollers are reusable as developing rollers. The regeneratedelastic roller surfaces are also seen not to be scratched due to thestep (1) in which the agglutinated stain is cracked.

Example 5

Adhesive rollers (C-5-1, C-5-2, C-5-3 and C-5-4) were produced in thesame way as in Example 1 except that the terpene phenol resin as anadhesion-providing resin was used in amounts of 5 parts by mass, 10parts by mass, 30 parts by mass and 50 parts by mass, respectively,based on 100 parts by mass of butyl rubber.

The adhesive roller C-1 was also produced in the same way as in Example1.

The adhesive force of each of these adhesive rollers was measured, andusing each adhesive roller, thirty regenerated elastic rollers wereproduced in the same way as in Example 1. Visual observations were madefor the thirty regenerated elastic rollers on whether or not theirsurfaces were scratched. All the regenerated elastic rollers were alsoevaluated in the same way as in Example 1. The evaluation results andthe adhesive force of each adhesive roller are shown in Table 5.

TABLE 5 Aggluti- adhe- nated stain Surface adhe- sive with or with orsive force without Fog- without Example: roller (N/m) cracks Ghosts gingscratches 5-1 C-5-1 0.1 with B B without 5-2 C-5-2 0.2 with A A without5-3 C-1 5 with A A without 5-4 C-5-3 20 with A A without 5-5 C-5-4 25with B B without

As shown in Table 5, in Examples 5-1 to 5-5, the agglutinated stain onthe roller surface can be removed to the extent that the regeneratedelastic rollers are reusable as developing rollers. The surfaces of theregenerated elastic rollers are also seen not to be scratched even whenthe adhesive rollers different in adhesive force are used.

Example 6

In the regenerated elastic roller manufacturing unit shown in FIG. 4,the adhesive roller 30 was set apart from the elastic roller 20, andonly the pressing roller 40 was pressed against the elastic roller 20under the same conditions as those in Example 1, where the elasticroller was rotated at 60 rpm for 15 seconds. Then, the pressing roller40 was set apart from the elastic roller 20, and only the adhesiveroller 30 was so brought into contact with the latter as to be under thesame conditions as those in Example 1, where the elastic roller wasrotated at 60 rpm for 15 seconds. The regenerated elastic roller thusobtained was evaluated in the same way as in Example 1. The resultsobtained are shown in Table 6.

TABLE 6 Agglutinated stain with or without cracks Ghosts Fogging Example6 with B B

From the results shown in Table 6, it is seen that the mode of Example 1in which the pressing roller and the adhesive roller are brought intocontact simultaneously with the elastic roller and the pressing againstthe agglutinated stain and the removal of the agglutinated stain crackedthereby are continuously carried out, is advantageous to the productionof high-quality regenerated elastic rollers.

Example 7

Prior to the step (1), elastic rollers with the agglutinated stainadhered thereon were left standing for 1 hour in a thermostaticenvironment kept at temperature shown in Table 7. Regenerated elasticrollers were produced in the same way as in Example 1 except that theseelastic rollers were moved from the thermostatic environment to anenvironment of normal temperature and an adhesive roller of 0.1 N/cm inadhesive force was immediately used. Evaluation was made in the sameway. Results obtained are shown in Table 7.

TABLE 7 Example: Cooling temperature Ghosts Fogging 7-1 No cooling B B(25° C.) 7-2 10° C. A A 7-3  0° C. A A 7-4 −10° C.   A A 7-5 −20° C.   BB

As shown in Table 7, it is seen that when previously cooling theagglutinated stain, regenerated elastic rollers with a higher grade canbe produced.

Example 8

Ten regenerated elastic rollers were produced in the same way as inExample 1 except that an adhesive roller (trade name: NU AdhesiveSilicone; manufactured by Techno Roll Co., Ltd.) whose rubber materialwas non-polar silicone rubber was used as an adhesive roller. Then, theregenerated elastic roller produced 10th was evaluated in the same wayas in Example 1. As a result, ghosts and fogging were both evaluated as“A”.

Example 9

A hundred regenerated elastic rollers were produced in the same way asin Example 1 except that an adhesive roller (trade name: NU AdhesiveSilicone; manufactured by Techno Roll Co., Ltd.) whose rubber materialwas non-polar silicone rubber was used as an adhesive roller. Then, theregenerated elastic roller produced 100th was evaluated in the same wayas in Example 1. As a result, ghosts and fogging were both evaluated as“B”. Making a comparison between this fact and the evaluation result inExample 1, it is seen that the adhesive roller using the butyl rubber asthe rubber material and the terpene type resin as the adhesion-providingresin can produce regenerated elastic rollers with a higher grade over alonger period of time.

Example 10

Elastic rollers (A-10-1, A-10-2 and A-10-3) were produced in the sameway as in Example 1 except that in Example 1, the proportion of thepolyurethane polyol prepolymer to the isocyanate was changed so that theNCO equivalent weight came to be the values shown in Table 8 below. Theelastic roller (A-1) was also produced in the same way as in Example 1.The agglutinated stain was formed on the surface of each of these fourtypes of elastic rollers by the method described in Example 1, and theprocessing of removing the agglutinated stain was repeatedly carried outfive times. Visual observations were made for each of the regeneratedelastic rollers obtained by the processing carried out five times, onwhether or not their elastic layer surfaces were scratched. Then, eachregenerated elastic roller was used for experiments on image formationand image evaluation under the same conditions as those in Example 1, toevaluate the quality of each regenerated elastic roller. The resultsobtained are shown in Table 8.

TABLE 8 Aggluti- NCO nated stain Surface equiv- with or with or Elasticalent without Fog- without Example: roller weight cracks Ghosts gingscratches 10-1 A-10-1 1.1 with A A without 10-2 A-1 1.2 with A A Without10-3 A-10-2 1.5 with A A without 10-4 A-10-3 1.6 with B B without

As shown in Table 8, it is seen that the regenerated elastic rollershaving elastic layers composed primarily of the resin obtained by mixingthe polyurethane polyol prepolymer and the isocyanate in the proportionsof from 1.1 to 1.6 in NCO equivalent weight are sufficiently durable torepeated regeneration processing.

Example 11

The part(s) by mass of urethane resin particles (C400 Transparent;particle diameter: 14 μm; available from Negami Chemical Industrial Co.,Ltd.) to be incorporated in raw-material fluids for forming surfacelayers of elastic rollers was changed as shown in Table 9. Then, elasticrollers (A-11-1, A-11-2, A-11-3 and A-11-4) each having surfaceroughness Ra as shown in Table 9 were produced. Regenerated elasticrollers were produced and evaluated in the same way as in Example 1except that these elastic rollers were used. The results obtained areshown in Table 9.

TABLE 9 Part(s) Aggluti- by mass of nated stain urethane with or Elasticresin Ra without Fog- Example: roller particles (μm) cracks Ghosts ging11-1 A-11-1 1 0.03 with B A 11-2 A-11-2 5 0.05 with A A 11-3 A-11-3 151.1 with A A 11-4 A-11-4 30 2.5 with A A

As shown in Table 9 above, regenerated elastic rollers with a highergrade can be obtained in Examples 5-1 to 5-5 in which the elastic rollersurface roughness Ra is 0.05 to 2.5 μm.

Example 12

The surface roughness Ra of the pressing roller surface was changed bycontrolling the time for which the roller was ground by means of acylindrical grinder, to produce pressing rollers (B-12-1, B-12-2 andB-12-3) each having surface roughness Ra as shown in Table 10. Thepressing roller (B-1) was also produced in the same way as in Example 1.In the same way as in Example 1 except that these pressing rollers wereused, thirty regenerated elastic rollers were produced for each pressingroller. The regenerated elastic rollers produced 30th were evaluated inthe same way as in Example 1, and were visually observed on whether ornot their surfaces were scratched. The results obtained are shown inTable 10.

TABLE 10 Aggluti- nated stain Surface with or with or Pressing Rawithout Fog- without Example: roller (μm) cracks Ghosts ging scratches12-1 B-12-1 0.05 with A B without 12-2 B-1 0.1 with A A without 12-3B-12-2 1.0 with A A without 12-4 B-12-3 5.0 with A A without

From the results shown in Table 10, it is seen that setting the pressingroller to be 0.1 to 5 μm in surface roughness Ra is advantageous to theproduction of high-quality regenerated elastic rollers.

Example 13 Production of Elastic Roller (A-13)

The following materials were mixed using an open roll mill to prepare anuncured rubber composition.

-   -   Epichlorohydrin-ethylene oxide-ally glycidyl ether terpolymer        (trade name: EPICHLOMER CG102; available from Daiso Co., Ltd.):        100 parts by mass.    -   Zinc stearate as a processing auxiliary: 1 part by mass.    -   Zinc oxide as a vulcanization accelerating auxiliary: 5 parts by        mass.    -   MT carbon black (trade name: THERMAX N990; available from        Cancarb Technologies Ltd.) as filler: 30 parts by mass.    -   Dipentamethylenethiram tetrasulfide (trade name: NOCCELER TRA;        available from Ouchi-Shinko Chemical Industrial Co. Ltd.) as a        vulcanizing agent: 2 parts by mass.

Then, a tube of the above uncured rubber composition was formed byextrusion using a vented extruder (a vented extruder of 50 mm indiameter, L/D: 16; manufactured by EM Giken Co.). Then, the tubeobtained was put into a vulcanizer and was primarily vulcanized at atemperature of 160° C. for 30 minutes with application of pressurizedwater vapor to obtain a rubber tube of 15 mm in outer diameter, 5.5 mmin inner diameter and 250 mm in length.

Next, a mandrel of 256 mm in length and 6 mm in diameter was readiedwhich was made of a free-cutting resulfurized steel (SUM) coatedbeforehand with a heat curable adhesive agent (trade name: METALOC U-20;available from Toyokagaku Kenkyusho Co., Ltd.) followed by drying. Then,this mandrel was inserted into the rubber tube and then heated at atemperature of 160° C. for 2 hours in a hot-air oven to secondarilyvulcanize the rubber tube and bond the mandrel and the rubber tubetogether. The rubber tube was cut at both ends so as to be 224 mm inlength in its axial direction. Thereafter, using an NC grinder, therubber tube was so ground as to come into a crown shape of 12.00 mm indiameter at end portions of the rubber part and 12.10 mm in diameter atthe middle portion of the rubber part.

Next, the following materials were mixed, and dispersed for 6 hours bymeans of a paint shaker to prepare a dispersion liquid.

-   -   Lactone modified acrylic polyol having a solid content of 70%        and a hydroxyl value of 90% (trade name: PLACCEL DC2009;        available from Daicel Chemical Industries, Ltd.): 150 parts by        mass.    -   Methyl isobutyl ketone: 500 parts by mass.    -   Silicone oil (trade name: SH28PA; available from Dow Corning        Toray Silicone Co., Ltd.) as a leveling agent: 0.05 part by        mass.    -   Conductive tin oxide powder (trade name: SN-100P; available from        Ishihara Sangyo Kaisha, Ltd.) as conductive particles: 30 parts        by mass.    -   Non-cross-linked acrylic particles (trade name: M-200; available        from Matsumoto Yushi-Seiyaku Co., Ltd.) as elastic particles: 30        parts by mass.

Then, the following materials were mixed, and stirred for 1 hour bymeans of a ball mill to prepare a surface layer coating fluid of 9 mP·sin viscosity.

-   -   The above dispersion: 370 parts by mass.    -   Isophorone diisocyanate, cyanurate type (trade name: BESTANATO        B1370; available from Degussa-Hulls AG): 25 parts by mass.    -   Hexamethylene diisocyanate, cyanurate type (trade name: DURANATE        TPA-B80E; available from Asahi Chemical Industry Co., Ltd.): 16        parts by mass.

The mandrel on the periphery of which the crown-shaped elastic layer wasbeforehand formed was immersed into the surface layer coating fluid, anddrawn up at a rate of 300 mm/min, followed by air drying for 30 minutes.Subsequently, this mandrel was reversed in its axial direction, and wasimmersed again in the surface layer coating fluid, and drawn up at arate of 300 mm/min. Then, the wet coating formed was dried at atemperature of 160° C. for 1 hour to form on the periphery of theelastic layer a surface layer of 20 μm in thickness. Thus, an elasticroller (A-13) of this Example was obtained.

The elastic roller (A-13) was set as a charging roller in anelectrophotographic process cartridge for an electrophotographic imageforming apparatus (trade name: Color Laser Jet 4700dn; manufactured byHP Ltd.). This was left standing for 24 hours in an environment of atemperature of 15° C. and a humidity of 10% RH. Thereafter, thiselectrophotographic process cartridge was mounted to the main body ofthe electrophotographic image forming apparatus, and in the environmentof a temperature of 15° C. and a humidity of 10% RH, images of 1% inprint percentage were reproduced until the remaining amount of thedeveloper came to be 20 g, to thereby adhere the agglutinated stain of adeveloper origin to the charging roller surface.

The charging roller whose surface the agglutinated stain of a developerorigin was adhered to was detached from the electrophotographic processcartridge, and air was blown against the surface to remove developercomponents therefrom. Thereafter, this roller surface was observed witha microscope to find that components coming from the developer were seento adhere much to the roller surface.

A regenerated elastic roller was produced in the same way as in Example1 except that this charging roller was used.

The regenerated elastic roller thus obtained was evaluated in thefollowing way.

The regenerated elastic roller of this Example was set as a chargingroller in an electrophotographic process cartridge for anelectrophotographic image forming apparatus (trade name: Color Laser Jet4700dn; manufactured by HP Ltd.). This electrophotographic processcartridge was left standing for 24 hours in an environment of atemperature of 15° C. and a humidity of 10% RH. Thereafter, thiselectrophotographic process cartridge was mounted to the main body ofthe electrophotographic image forming apparatus. In the environment of atemperature of 15° C. and a humidity of 10% RH, halftone images werereproduced as images for evaluation on charge lines.

If images are formed by using a charging roller whose surface theagglutinated stain of toner has been formed on, the charge quantity oftoner on the photosensitive drum becomes short. If halftone images areformed in this state, the potential on the photosensitive drum maybecome non-uniform, so that charge lines may be formed. Accordingly, thelevel of such charge lines may be used as an index of how far thecontamination of surface has been eliminated by the regenerationprocessing. As for charge lines resulting from contamination of thecharging roller surface, image formation was carried out to make anevaluation according to the following criteria.

A: Charge lines are not seen at all in visual observation.

B: Charge lines are slightly seen.

C: Charge lines are clearly seen.

D: Many charge lines occur further in the lengthwise direction.

The results obtained are shown in Table 11.

Comparative Example 3

Image formation was carried out to make an evaluation in the same way asin Example 13 except that the charging roller whose surface theagglutinated stain of toner was formed on was not subjected to theregeneration processing. The results obtained are shown in Table 11.

Comparative Example 4

In the same way as in Example 13 except that the pressing roller was notset up, the regeneration processing was performed, and image formationwas carried out to make an evaluation. The results obtained are shown inTable 11.

TABLE 11 Step(s) of regeneration processing carried out Charge linesExample 13 First & second steps A Comparative Not carried out C Example3 Comparative Second step only B Example 4

It is seen from Table 11 above that the regenerated elastic rolleraccording to the present invention is also usable as a charging roller.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims priorities from Japanese Patent Application No.2007-011914 filed on Jan. 22, 2007 and Japanese Patent Application No.2008-008346 filed on Jan. 17, 2008, which are herein incorporated byreference.

What is claimed is:
 1. A regenerated elastic roller manufacturingprocess comprising the step of removing an agglutinated stain of adeveloper origin adhered to the surface of an elastic roller, saidelastic roller provided with a mandrel and an elastic layer, whereinsaid step comprises the steps of: (1) rotatably supporting the elasticroller, a pressing roller and an adhesive roller in a jig, with theelastic roller positioned between the pressing roller and the adhesiveroller; (2) rotating the rollers; (3) pressing the pressing rolleragainst the surface of the elastic roller so as to crack theagglutinated stain which is kept in a hardened state on the surface ofthe elastic roller; and (4) removing the agglutinated stain cracked inthe step (3) from the surface of the elastic roller by pressing theadhesive roller against the surface of the elastic roller; wherein theelastic roller, the pressing roller and the adhesive rollers havediameters Da, Db and Dc respectively, which satisfy a relationshipDc<Da<Db.
 2. The regenerated elastic roller manufacturing processaccording to claim 1, wherein the elastic roller, the pressing rollerand the adhesive roller have Asker-C hardnesses Ha, Hb and Hc,respectively, which satisfy a relationship of Hc<Ha<Hb.
 3. A regeneratedelastic roller manufacturing process comprising the step of removing alaminar agglutinated stain of a developer origin adhered to the surfaceof an elastic roller, said elastic roller provided with a mandrel and anelastic layer as a surface layer, wherein said step comprises the stepsof: (1) rotatably supporting the elastic roller, a pressing roller andan adhesive roller in a jig, with the elastic roller positioned betweenthe pressing roller and the adhesive roller; (2) rotating the rollers;(3) locally deforming the elastic roller on the surface of which thelaminar agglutinated stain whose flexibility is lower than the elasticroller has been adhered, by pressing the pressing roller against thesurface of the elastic roller, and cracking the agglutinated stain whichis kept in a hardened state, and (4) removing the agglutinated staincracked in the step (3) from the surface of the elastic roller bypressing the adhesive roller against the surface of the elastic roller;wherein the elastic roller, the pressing roller and the adhesive rollerhave diameters Da, Db and Dc respectively, which satisfy a relationshipDc<Da<Db.